...reference into local variable| astore | |
| index |
Description
The index is an unsigned byte that must be a valid index into the local variables of the current frame (§3.6). The objectref on the top of the operand stack must be of type returnAddress or of type reference. It is popped from the operand stack, and the value of the local variable at index is set to objectref.
Notes
The astore instruction is used with an objectref of type return-Address when implementing Java's finally keyword (see Section 7.13, "Compiling finally"). The aload instruction cannot be used to load a value of type returnAddress from a local variable onto the operand stack. This asymmetry with the astore instruction is intentional.
The astore opcode can be used in conjunction with the wide instruction to access a local variable using a two-byte unsigned index.